WS 5449 then SQ 1491 at San Francisco
Detroit → San Francisco → New York JFK
Timetable, San Francisco time
18:21WS 5449 from Detroit at the gate
22:56SQ 1491 to New York JFK leaves the gate
4 h 35 apart on the timetable
The last days
WS 5449 and SQ 1491 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.